ADSL (Asymmetric Digital Subscriber Line) is a modem technology that transmits multimedia and high speed data over existing twisted-pair telephone lines concurrently with Plain Old Telephone Service (POTS) signals. VDSL is a higher speed variation of ADSL. The multimedia and high speed data are at a higher frequency than the POTS signals, and components have been developed that can split the higher frequency multimedia and/or data from the lower frequency POTS signal and/or vice versa at either end of the transmission path. IDSL is a variation wherein the multimedia and/or high speed data is transmitted concurrently with an ISDN signal instead of the POTS signal. The ISDN signal, while at a higher frequency than the POTS signal, is at a lower frequency than the multimedia or high speed data signal. Other variations may exist or be developed where signals of differing frequencies are transmitted over existing twisted-pair wiring to a subscriber. The term xDSL will be used herein to refer generically to these different versions of transmitting higher frequency signals (e.g. ADSL, VDSL, etc.) over twisted pair concurrently with a relatively lower frequency signal (e.g., POTS, ISDN, or out-of-band signaling used in special services). The terms "first signal" and "second signal" will be used herein to refer generically to at least two different frequency signals transmitted concurrently over twisted-pair wiring that are intended to be separated, or split, at the subscriber. The term "combined signals" will be used to refer to both the first and second signals combined over a line.
An xDSL architecture connects an xDSL modem on each end of a twisted-pair telephone line, that is, at the "central office" (or node or remote terminal) and at the premises of the subscriber (or customer). The terms "splitting" or "splitter" are used to refer to a circuit or component, for example, a low pass filter or low pass and high pass filter combination, that separates the first signal from a combined signal, in the example of a low pass filter, and that separates both the first and second signals from the combined signal in the example of the low pass and high pass filter combination. Components other than low pass and high pass filters may exist or be developed that also perform this splitting function. The particular structure and nature of the various splitter circuits or components are not necessary to the present invention other than the fact that they "split" the combined signal and are interconnected into an xDSL network in some manner at the customer end of the network.
Co-pending applications Ser. Nos. 09/001,565 and 09/001,678 which issued on Feb. 15, 2000, as U.S. Pat. No. 6,026,160, disclose splitter modules for use in the Network Interface Device (NID) typically located on the outside of the subscriber residence. It may be desired to locate the splitter inside the residence and therefore a need exists for appropriate packaging of the splitter such that it can be readily interconnected with existing inside telephone wiring installations.
Existing inside, or premises, wiring installations typically comprise two twisted wire pairs routed throughout the premises ("red/green" and "yellow/black") with typically only the red/green actually wired to the various wall jacks in the home. In some existing installation, an "indoor is NID" is used that appears generally like a common wall jack face and faceplate but additionally includes a demarcation plug and jack. U.S. Pat. Nos. 4,488,008, 4,647,725 and Des. No. 275,667 show examples of indoor NIDs that are specifically designed for use indoors to mount in a wall and appear somewhat like a telephone outlet face plate. Indoor NIDs are especially appropriate for use in apartment buildings and other locations where protection is provided in Building Entrance Terminals.
A splitter sold by Alcatel under the designation "A1000 ADSL Remote Splitter" is disclosed as being installed in an outdoor NID. This splitter has a wire pair pigtail for being connected to the wire pair carrying the combined signal and two pairs of screw terminals for connection to two wire pairs, each carrying a respective one of the first or second signals from the splitter. The Alcatel splitter is not readily used indoors by itself in that hard wiring of the pigtail and screw terminals is a cumbersome process and it is not apparent how the splitter would be interconnected with existing indoor telephone wiring installations or how the splitter would be protected from casual contact or physical damage.
A need exists for an xDSL splitter module that can be readily interconnected with existing indoor telephone wiring installations and provide protection from casual contact and physical damage.